Depending on a variety of conditions, normally-on transistors may have superior electrical characteristics than normally-off transistors within the same semiconductor substrate material. As an example, this may be due to interface properties between a gate insulator and a semiconductor channel region of a Field Effect Transistor (FET).
A cascode circuit of a normally-on transistor in a first semiconductor die and a normally-off transistor within a second semiconductor die allows to set up a normally-off semiconductor switch that may include beneficial electrical properties of the normally-on transistor such as low-on resistance or high-reverse blocking capabilities.
When forming a normally-off semiconductor switch using a cascode circuit including a normally-off transistor and a normally-on transistor, a plurality of requirements having an impact on the device reliability have to be met, e.g., avoidance of critical operation conditions such as avalanche breakdown or avoidance of generation of oscillations.
With regard to a semiconductor switch including a normally-on transistor and a normally-off transistor, a need exists for an improved device reliability.
For these and other reasons, there is a need for the present invention.